1. Field of the Invention
The present invention relates to a dynamo-electric machine rotor equipped with a magnet portion and provided between adjacent triangular magnetic poles for reducing the leakage of magnetic flux between the triangular magnetic poles, and a method of manufacturing same.
2. Description of Related Art
FIG. 10 is a sectional side elevation of a conventional vehicular AC generator and FIG. 11 is a perspective view of a rotor shown in FIG. 10. The AC generator is equipped with: a case 3 comprising of a front bracket 1 and a rear bracket 2 made of aluminum; a shaft 6 provided in the case 3 and having a pulley 4 fixed at one end thereof; a Randell-type rotor 7 secured to the shaft 6; fans 5 secured to both side surfaces of the rotor 7; a stator 8 secured to the inner wall surface of the case 3; a slip ring 9 secured to the other end of the shaft 6 for supplying current to the rotor 7; a pair of brushes 10 in sliding contact with the slip ring 9; a brush holder 11 which holds the brushes 10; a rectifier 12 electrically connected the stator 8 to for changing alternating current generated in the stator 8 to direct current; a heat sink 17 fitted onto the brush holder 11; and a regulator 18 bonded to the heat sink 17 for adjusting the magnitude of the AC voltage generated in the stator 8.
The rotor 7 is comprises by a rotor coil 13 through which current flows to generate magnetic flux, and a field core assembly 14 that covers the rotor coil 13 and in which magnetic poles are formed by the magnetic flux. The field core assembly 14 is a pair composed of first field core member 21 and second field core member 22 which are alternately meshed. The first field core member 21 and the second field core member 22 are made of iron. The first field core member 21 has triangular magnetic poles 23, and the second field core member 22 has triangular magnetic poles 24. A hexahedral magnet 19 is provided between adjacent ones of the triangular magnetic poles 23 and 24 in an orientation that reduces the leakage of magnetic flux between the triangular magnetic poles 23 and 24.
The stator 8 is provided with a stator core 15 and a stator coil 16 composed of a conductor wound around the stator core 15, in which alternating current is generated as the magnetic flux from the rotor coil 13 changes as the rotor 7 rotates.
In the vehicular AC generator configured as set forth above, current is supplied from a battery, not shown, to the rotor coil 13 via the brushes 10 and the slip ring 9 so as to generate magnetic flux. The triangular magnetic poles 23 of the first field core member 21 are magnetized to the N pole (positive polavity), while the triangular magnetic poles 24 of the second field core 22 are magnetized to the S pole (negative polavity).
The pulley 4 is driven by an engine and the rotor 7 is rotated through the shaft 6, so that a rotary magnetic field is supplied to the stator coil 16, generating an electromotive force in the stator coil 16. This AC electromotive force is rectified into direct current through the rectifier 12 and the voltage magnitude thereof is adjusted by the regulator 18 before it is supplied to the battery.
In a conventional rotor 7 of the vehicular AC generator, the hexahedral magnet 19, which has been magnetized in a direction so as to reduce the leakage of magnetic flux between the triangular magnetic poles 23 and 24, is secured to adjacent triangular magnetic poles 23 and 24 by using an adhesive agent. More specifically, the hexahedral magnet 19 is secured so that the side opposed to the triangular magnetic pole 23 magnetized to the N pole constitutes the N-pole surface of the magnet 19, while the side opposed to the triangular magnetic pole 24 magnetized to the S pole constitutes the S-pole surface of the magnet 19. This makes it possible to reduce ineffective magnetic flux, which leaks between the adjacent triangular magnetic poles 23 and 24 and therefore does not contribute to the power generation of the AC generator, so that the power generating efficiency of the AC generator is thereby increased.
The magnets 19, however, are each discretely positioned at twelve points between the triangular magnetic poles 23 and 24. Therefore, a lot of time is required to attach the magnets 19, leading to the problem of poor assembly efficiency.